There are presently few technologies with the ability to non-invasively image the lymphatic system in vivo and in real time, and there is a paucity of imaging technologies with the sensitivity and temporal resolution to discriminate lymphatic function. Because lymph provides little endogenous contrast, lymphatic architecture and function cannot be probed directly with ultrasound, MR or CT techniques and the 2105-09701 lymphatic vasculature is not readily accessible for administration of the milliliters of contrast agent needed for MR or CT angiography, making aberrant lymph architecture difficult to routinely assess. Currently, lymphoscintigraphy which will visualize the structures involved but long integration times associated with gamma cameras prevent imaging of lymphatic function and the image resolution limits visualization of fine lymphatic vasculature. The ability to image lymphatic function non-invasively in animals and humans using near-infrared (NIR) fluorescence has been described for the purposes of detecting early signs of lymphedema following cancer treatment and evaluating the lymphatic response to lymphedema therapy (see for example, U.S. Pat. Nos. 5,865,754; 7,054,002; 7,328,059; US Patent Application Publication Nos: 2007/0286468; 2008/0056999; 2008/0064954; 2008/0175790 and 2011/007140). Non-invasive imaging of active lymph drainage, following intradermal administration of microgram amounts of indocyanine green (ICG), a green dye used for hepatic clearance and ophthalmological indications, has been done by using its NIR fluorescence properties for optical imaging. Another application for these imaging devices resides for intraoperative detection of disease markers that could demark tumor margins or cancerous tissues that would not otherwise be detected. The ability to use a phantom to determine whether the device and the molecularly targeted fluorescent imaging agent can together provide adequate signals for optimal performance requires validation with a stable phantom.
In yet another application, far red gene reporters are being used to demark diseased tissues in preclinical animal models in drug discovery programs. A phantom to underscore the performance and robustness of the imaging results so as to draw robust research conclusions is needed. That is to say a phantom that can provide a reflectance standard.
Consequently, there is continuing interest in fluorescence based non-invasive imaging methods such as NIR, far-red fluorescence and imaging agents for dynamically assessing lymph function in vivo to facilitate, direct and evaluate therapies for the treatment of lymphatic disorders and image guided therapies. However there has been little work to assess the performance of either time-dependent or time-independent measurement systems designed to collect fluorescence emanating from intact biological tissues. In addition, there are no metrics for assessing the sensitivity of such fluorescence imaging systems currently deployed in clinical studies. Because of the rapid evolution of fluorescence devices such as NIR, for use in humans, there are no metrics for assessing the sensitivity of these fluorescence imaging systems and a clear and unmet need to characterize devices, evaluate measurement sensitivity, especially when translating into humans with different imaging devices.